Known air filter arrangements for a combustion engine of a truck often have an extra air outlet connected to an air compressor for various compressed air consumers on board the vehicle. The hose from the extra air outlet to the compressor is at present usually fitted to a pipe stub on one or more ducts in a blow-moulded air duct system which leads the air from the engine air outlet to the engine.
The configuration of the blow-moulded air duct system is thus complicated and the air flow through the air duct is adversely affected such that the pressure drop increases across the system, leading to higher fuel consumption of the engine. When the compressor draws air in, it takes part of the air which is on its way on into the engine, thereby also disrupting the measurement of the mass flow to the engine.